Leca UK has provided its expertise and materials to the construction of the new Queensferry Crossing.
Leca UK has provided its expertise and materials to the construction of the new Queensferry Crossing, the 2.7 km-long bridge linking Edinburgh and Fife.
The Crossing Bridge, which is the longest three tower, cable-stayed bridge in the world and also the largest to feature cables which cross midspan, officially opened to traffic on 4 September 2017.
Leca UK, who specialises in the production of Leca® lightweight expanded clay aggregates, has supplied 5500m3 of their lightweight aggregate Leca® LWA 10-20mmR to be used in the reinforcement of the bridge’s supporting structure on the north side of the A90.
Leca’s work in the area involved supplying the Lightweight aggregate used to raise part of the existing A90 mainline levels and widening westwards. The traditional solution of direct placing conventional fill materials on the existing A90 and the adjacent ground would have applied additional loads on the soft peat and underlying alluvial materials, resulting in unacceptably large settlements, as well as causing environmental issues.
Leca Lightweight Aggregate’s (LWA) density is around 25% of that of conventional fills, so the team opted for excavating the existing ground to a depth that allowed for replacement and filling up to the new design level. This resulted in a net load of zero being applied to the underlying soft strata, which assured that the post construction settlement was kept to a minimum and differential settlement issues compensated.
Leca’s LWA brought additional short and long-term benefits, such as significant time saving in construction duration, which resulted in minimal disruption and delays to existing road users. This came with environmental benefits, as there was reduced congestion and vehicle emissions.